Prove it and that your compiler is fully C compliant and can handle all possible inputs GCC can accept (and optimize as well as GCC), then we'll talk. Only then will your compiler risk leaving GCC behind.
Auto vectorization would need extensive -O3 opts, which I dont do yet. No ssa, no escape analysis. The compiler should stay fast. And I prefer manual vectorization via attributes. Still better than using the insane and platform dependent SSE/neon apis, everyone else is using. See the torture/vect/ tests. They all pass